88 convertible 53K miles. starts fine when cold...hot days won't restart. Lift hood...restarts after 20-30 minutes. Figured vapor lock, but yesterday took over an hour before restart edsuccessfully.

 

It's probably getting flooded. Have you cleaned the injectors recently? Installing a fuel cut switch also helps tremendously

 

I would first start by running a proper compression test with a rotary compression tester. Ibwould also send the injectors out to a company like www.witchhunter.com and have them tested, cleaned, and flow tested. Leaking injectors can cause flooding after a warm engine sits. You may also want to consider a spark plug and wire replacement if you have not done so. A fuel pressure test would also be useful. Would determine if you have the proper pressure and ensure there is no pressure bleed off.

 

Appreciate the advice. Associated is fuel smell (which seems to linger for 5-10 minutes), high initial idle (which calms with throttle blip) and stalling, all after cold start, til engine at operating temp.

 

This is not a fix but it might help to start it when it's hot. You can press the gas pedal to the floor (WOT) and then try to start it. This way the fuel pump does not work and it helps a lot if you have a flooded engine.

 

If memory serves correctly, that is only a factory feature on the S5. Since he has an 88, this doesn't apply to him. Only S4 with an ECU upgrade (even RTEK) can do that.

 

I have an '86 with 35K miles and I have a problem hot starting it sometimes too. I find holding the throttle down a bit will get it over the initial hiccup then it'll run fine. These cars just do this sometimes, it doesn't necessarily mean anything is wrong with it.